This invention relates to X-ray apparatus in which the X-radiation tube and the image intensifier or other radiation receptor are mounted at the ends of two parallel arms of a generally U-shaped support such as is shown in U.S. Pat. No. 3,892,967. The two radiation means are optically aligned on a common radiation axis. In radiological examination of a subject the U-shaped support is turned in a bearing about a rotational axis parallel to the arms on which the X-ray tube and radiation receptor are mounted and through which the radiation axis passes. It is necessary that the rotating assembly of U-shaped support and radiation source and receptor be kept in balance with respect to the rotational axis to reduce bearing friction, to allow the assembly to rest motionless in equilibrium, and also to permit manual rotation of the assembly. On the other hand it is desirable to adjust the X-ray tube along the radiation axis toward and away from the rotational axis which would destroy the equilibrium of the assembly unless adjustment of the X-ray tube weight is compensated by adjustable counterweighting.
Adjustable counterweighting may be achieved by moving sliding weights on cables or the like as shown in the aforementioned patent. However, if both the radiation source and receptor are to be adjusted, there may be insufficient space for the counterbalancing system on or in the arms of the U-shaped support.
Accordingly it is the object of the present invention to provide a counterbalancing system which requires a minimum of space and allows counterbalancing of both the radiation source and the radiation receptor.